Epoxy polymer surface modification through wet-chemical organic surface synthesis for adhesion improvement in microelectronics

Wet-chemical surface synthesis reactions were performed on thin epoxy layers for usage as a build-up layer in microelectronics. The synthesis reactions, based on heterocyclic organic coupling agents, were used to imprint iminodiacetic acid and imidazole groups at the surface of the epoxy polymer, based on nucleofilic substitution reactions. The synthesized surfaces are examined by means of XPS and ATR-IR measurements. XPS measurements illustrate that the identity of the chemical groups near the interface (top 10 nm of the polymer surface) has been altered by the procedure. After the synthesizing procedure, copper was electrochemically deposited using an electroless/electroplating scheme. The type of groups located at the surface of the polymer has a pronounced influence on the adhesion strength of electrochemically deposited copper. Hence the interface between the copper and epoxy determines the adhesion properties between both. The surfaces of the peeled polymer layers and the backs of the copper strips were examined by XPS after the peeling procedure in order to determine the interface failure mechanism.